How to Set Up S/MIME Email Encryption with a Signed Certificate on iPhone


Security and privacy are critical issues for every business today. You don’t need to work for a bank to be concerned.  From a digital media agency to an online pet store, it’s important that only the people you choose see your emails.

Campaign managers at a digital advertising agency are especially conscious of potential problems from competitors stealing information from customers. That’s why many advertisers at a digital agency insist on using email encryption with a signed certificate. It adds a layer of security in an age of digital prying.

The Benefits of Email Encryption

When you use encryption software, you are able to:

  • Sign you messages. This proves you were the sender and that the message your recipient reads is the actual one you sent.
  • Encrypt your messages. Only the person you send it do is able to read it.

But successfully installing and using the software can be a challenge. Even members of a digital ad agency, with easy access to techies, have been known to sigh heavily when going through the process.

For Apple devices, S/MIME is the software of choice. Apple Mail on OS and iOS support it, as well as Outlook on Windows. And there are numerous mail programs that work with S/MIME.

To make it easier for you, here is an easy step-by-step set of instructions for adding and using email encryption for your iPhone. The process has four parts:

  • Getting your certificate
  • Installing it on Apple Mail
  • Installing it on your iOS device
  • Using it successfully

    Getting a S/MIME Certificate


    The first step is getting a Class 1 SSL certificate for your specific email address. It needs to be signed by a trusted Certificate Authority, or CA. A certificate you generate yourself has no trust value.

    For almost everyone, a Class 1 certificate is as high as you need to go. StartCom and Comodo both offer a Class 1 certificate free for personal email.

    For a certificate from Comodo:

    1. go to
    2. Fill out the form with your name, email address and country.
    3. Type in a Revocation Password. Make it complex and be sure to write it down somewhere.
    4. Accept the terms and click Next.
    5. Comodo will send you an email with a link to your download.
    6. In the email, click the red box (Click and Install Comodo Email Certificate) which starts the automatic install process. You can only install the certificate on the same computer that you use to make the request for the certificate.

    For a certificate from StartSSL:

    1. Go to
    2. Click Start Now for Free SSL Certificate.
    3. Click Sign-up.
    4. Choose your country and fill in your email address. Click Send Verification Code.
    5. When you get the email, copy the verification code.
    6. Paste it into the Verification Code box. Click Sign Up.
    7. This starts the automatic installation. When it’s finished, the screen will say “The login certificate is installed in your computer.” On your Mac, it is in the Keychain Access.

    Installing the S/MIME Certificate


    To install the S/MIME certificate on your iPhone, you need to export it from your computer to your phone. Windows makes this easy with the Certificate Export Wizard.

    Exporting your certificate:

    1. Click Win + R, type in certmgr.mac, which opens the certificate manager.
    2. Choose Certificates – Current User à Current User à Personal à Certificates. Locate the email address you want to use.
    3. Right click on the email address, then select All Tasks à Export… This actually starts the Certificate Export Wizard.
    4. Click the Yes button when the Wizard asks if you want to export the certificate.
    5. Accept the file format Personal Information Exchange – PKCS #12 (.pfx).
    6. Choose a reliable password and write it down. Anyone with your .pfx file and password will be able to send an email that looks like it is signed by you.
    7. Choose a filename.
    8. Click Finish. At this point your S/MIME certificate is in a file that is password protected. It is ready for you to import it and use it on your iPhone.

    Getting it on your iPhone:


    1. Email the certificate to yourself.
    2. Open the email on your iPhone.
    3. Click the .pfx attachment, and install it.

    Using S/MIME in iOS Mail

    1. Go to Settings > Mail, Contacts and Calendars. Choose your mail account.
    2. Choose Account > Advanced Settings à S/MIME.
    3. Select Yes for both the option Sign and the option Encrypt by Default. Select your new certificate for each.
    4. Check it by sending an email message. If it is signed, there will be an open padlock graphic next to the name of the recipient.
    5. Toggle encryption on or off by tapping the padlock.

    There it is, the steps you need to take to successfully install and use S/MIME email encryption with a signed certificate on your iPhone. Whether you are part of a digital marketing agency or have an online shop, it will help ensure privacy and security when you communicate with coworkers and customers.

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